Fluid-blast circuit interrupter with improved electromagnetic driving means and lost motion means



Aug. 18, 1970 R. E. FRINK FLUID-BLAST CIRCUIT INTERRUP TER WITH IMPROVED ELECTROMAGNETIC DRIVING MEANS AND LOST MOTION MEANS 4 Sheets-S heet 1 Filed Sept. 1, 1966 FIG.

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INVENTOR Russell E.Frink.

ATTOR NEY 3,524,957 VED ELECTROMAGNETIC MEANS R. E. FRINK T INTERRUPTER Aug. 18, 1970 FLUID-BLAST CIRCUI WITH IM DRIVING MEANS AND LOST MOT Filed Sept. 1, 1966 4 Sheets-Sheet 2 FIG.2.

Aug. 18, 1970 R. E. FRINK 3,524,

FLUID'-BLAST CIRCUIT INTERRUPTER WITH ROVED ELECTROMAGNEI'IC DRIVING MEANS AND LOST M ON MEANS Filed Sept. 1, 1966 4 Sheets-Sheet s WW. i'.' Q ALA i,

Filed Sept. 1, 1966 FLUID-BLAST CIRCUIT INTERRUPTER WITH IMPROVED ELECTROMAGNETIC DRIVING MEANS AND LOST MOTION MEANS 4 Sheets-Sheet r 7 V CLOSED b P I T I 0 N '9 r u I3 IO 24- 1 FIG.7.

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a? J 9 '3 /l/l/I/I/l/I/I/I/IY/h v 22 35 Q? OPERATING MECHANISM -33 -24 57 44 -F|G.8. //Al\\\\\ 46 a? CLOSING 2| OPERATION 25 OPERATING MECHANISM 53 United States Patent 3,524,957 FLUID-BLAST CIRCUIT INTERRUPTER WITH IMPROVED ELECTROMAGNETIC DRIVING MEANS AND LOST MOTION MEANS Russell E. Frink, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 1, 1966, Ser. No. 576,615 Int. Cl. H01n 33/91, 33/42 US. Cl. 200148 7 Claims ABSTRACT OF THE DISCLOSURE A fluid-blast type of circuit interrupter is provided having a movable piston reciprocating within an operating cylinder and carrying a moving driving or accelerating coil therewith. The movable contact structure and a fluid-directing hollow orifice member additionally move with the moving piston to thereby compress fluid, such as sulfur hexafluoride (SP gas, within the operating cylinder and force such compressed fluid through the hollow insulating orifice member and into engagement with the established arc to effect the latters extinction.

A stationary accelerating coil, embedded in the insulating head of the stationary operating cylinder, is electromagnetically attracted to the movable driving coil carried by the fluid-driving piston, so that during the interruption of heavy fault currents, the operating mechanism, driving said piston mechanically, is assisted in its mechanical effort.

An auxiliary contact structure, responsive to the initial movement of the [fluid-driving piston, switches the two accelerating coils electrically into the series circuit, so that they are electromagnetically attracted together. The auxiliary contact structure includes a movable actuating member (25) with movable auxiliary contacts having a lost-motion connection with a movable conducting bridging member (44) also carrying movable auxiliary contacts. The bridging member (44) drives the movable piston.

The arrangement is such that during the closing operation, one of the accelerating coils is not connected serially into the circuit even though the other accelerating coil may be so connected. Thus, the attractive electromagnetic force acting in the opening direction is eliminated during the closing stroke of the interrupter to pre vent its stalling during such closing motion due to prestriking of the arc during closing.

This invention relates, generally, to fluid-blast circuit interrupters and, more particularly, to improved fluidblast circuit interrupters having electromagnetic fluiddriving means associated therewith.

In United States patent application filed Sept. 1, 1966, Ser. No. 576,616 by Russell E. Frink, and assigned to assignee of the instant application, there is illustrated and described novel fluid-blast circuit interrupters utilizing electromagnetically-operated piston means to inject fluid into the arc during the opening operation, utilizing the energy present in the fault current passing through the circuit interrupter.

It is a general object of the present invention to improve upon the general type of fluid-blast circuit interrupter of the aforesaid application rendering it of simplified construction and more suitable to more eifective fluid-blast operation.

Another object of the present invention is to provide an improved fluid-blast circuit interrupter utilizing electromagnetic energy passing through the circuit inter- 3,524,957 Patented Aug. 18, 1970 rupter to actuate the piston means, in which the fluid blast is injected through a fluid-directing orifice associated with the movable contact structure of the circuit interrupter.

Another object of the present invention is to provide an improved contact-operating arrangement which will be adaptable to open the several contacts in the correct sequential manner to thereby insert the two accelerating coils into the circuit at the proper time.

Still another object of time present invention is to provide an improved fluid-blast circuit interrupter utilizing a stationary accelerating coil and a moving driving coil associated with the movable piston structure, with improved auxiliary separable transfer contact means for inserting the two accelerating coils into the circuits at the proper time.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIG. 1 is a vertical sectional view, partially in side elevation, of a fluid-blast type of circuit interrupter incorporating the principles of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a considerably enlarged vertical sectional View taken through the interrupting structure of the circuit interrupter illustrated in FIG. 1, again the contact structure being illustrated in the closed-circuit position;

FIG. 3 is a fragmentary sectional view taken along the line IIL-III of FIG. 2;

FIG. 4 is a fragmentary sectional view taken substantially along the line V-IV of FIG. 2;

FIG. 5 is a lower end view, partially in section, of the operating cylinder end and associated auxiliary contact structure, as viewed from the direction VV of FIG. 2;

FIGS. 68 diagrammatically illustrate the electrical connections for the two accelerating coils respectively in the closed position, the partialy open position and during the closing operation; and,

FIG. 9 is a fragmentary side elevational view illustrating the lost-motion connection between the driving operating member and the conducting bridging member fixed to the piston structure.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a fluid-blast type of circuit interrupter. Generally, the fluid-blast circuit interrupter 1 includes a top and line terminal casting 2, an upstanding insulating casing 3, of some suitable weatherproof material, such as porcelain, and a lower mechanism casing 4. As Well known by those skilled in the art, the several casings may have flanged bolted connections to secure them together, as shown in FIG. 1. The casing contains, preferably, an ambient gas pressure of the order of 60 p.s.i. of sulfurhexafluoride (SP gas. Of course, other suitable arcextinguishing gases could be used.

Extending downwardly interiorly of the upper line terminal casting 2 is a stationary tubular venting contact 6 making contacting engagement with a plurality of circumferentially-disposed contact fingers 7 (FIG. 2), which are carried by a movable piston member 9 reciprocally operating within an outer operating cylinder 10. The operating cylinder 10 is maintained in a stationary position within the casing 3 by having a radially-outwardly extending flange portion 10a thereof, being bolted to a stationary support ring 5,'the latter, in turn, being supported within a recess 3a of the casing 3. As more fully described hereinafter, the fluid-moving piston member 9 reciprocally operates within the operating cylinder 10 to compress a suitable fluid, such as sulfur-hexafluoride (SP gas, within the region 11 below the movable piston member 9 and force the compressed SF gas into the established arc to effect its extinction.

In more detail, as shown in FIG. 3 of the drawings, the conducting portion 9b of the movable piston 9 has apertures 9b provided therein to permit gas flow from the region 11 upwardly through the openings 9b and through the tubular orifice member 18 to direct fluid into the are.

As shown more clearly in FIG. 2, the lower end 12 of the operating cylinder is closed, and serves to define the compressed region 11. Embedded within an insulating portion 9a of the movable piston 9 is an accelerating, or driving coil, designated by the reference numeral 13. and having a strap connection 14 and bolt means 15 to electrically connect the same to the conducting portion 9b of the movable piston member 9. As shown more clearly in FIG. 2, the conducting portion 911 of the movable piston member 9 serves additionally to seat a plurality of circumferentially-disposed contact fingers 7 and, also supports a centrally-disposed movable arcing contact 16, all collectively defining a movable contact structure, generally designated by the reference numeral 17. It will, therefore, be apparent that the movable piston 9, driving or accelerating coil 13, finger contacts 7, arcing tip 16 and an insulating fluid-directing orifice member 18 all move downwardly together as a bodily unit, as effected by suitable driving means, more particularly described hereinafter.

As mentioned previously, one end of the driving coil 13 is connected by the bolt conection 15 to the movable contact structure 17, comprising the contact fingers 7 and the arcing tip 16. The other end or terminal of the driving coil 13 is electrically connected by a connecting strap 19 and an elongated conducting bolt 20 to a movable auxiliary contact 21, the latter making contacting engagement in the closed-circuit position, as shown, with a second movable auxiliary contact 22 carried by an elongated conducting actuating or operating member 25, more clearly illustrated in FIG. 5 of the drawings. As shown in FIGS. 4 and 5, the operating member or first movable auxiliary transfer contact member 25 is channel-shaped in configuration.

The conducting actuating transfer member 25 has a pair of oppositely-extending trunnions 27, which are pivotally connected to a pair of insulating operating links 28 (FIG. 1), which, in turn, are pivotally connected, as at 29, to the arms 23 of a main rotative operating crankshaft 30. As shown in FIG. 1, the main operating crankshaft 30 extends externally of the circuit-interrupter casing structure, and is operated by a crank-arm 31 connected to a suitable operating mechanism, diagrammatically represented by the reference numeral 33.

The elongated conducting actuating member 25 additionally has another movable auxiliary contact 35 making seperable engagement with a movable auxiliary contact 37 disposed at the lower end of a conducting piston rod 24 driving the piston 9. As shown, the auxiliary contact 37 is electrically connected to the conducting portion 9b of the piston 9, by way of conducting operating rod 24, and hence to the movable contact structure 17 of the interrupter 1.

The piston structure 9 additionally carries an outer movable conducting tube 40, insulatingly surrounding the rod 20, which passes through an opening 41 in the lower closed end 12 of the operating cylinder 10, and is clamped by a movable conducting bridging clamping member or second movable auxiliary transfer contact member 44, which serves to electrically interconnect the conducting tube 24 with the conducting tube 40. As shown in FIG. 5,

the ends of the conducting bridging transfer member 44 are bifurcated, as at 44a, and have stud bolts 45 and nuts 47 passing through holes provided in the bifurcated ends thereof to clamp the tubes 24, 40.

The conducting bridging member 44 has a lost-motion connection 46 with the actuating member 25. In more 4 detail, the bridging member 44 has outwardly-extending undercut insulating nuts 47, which pass through elongated slots 50 provided in the actuating member 25 shown in FIG. 9.

Embedded in the lower closed end 12 of the operating cylinder 10 is a stationary accelerating oil 52, which has one end 53 (FIG. 5) connected to a stationary contact support 55 constituting a lower line terminal of the interrupter 1. The stationary contact support 55 comprises a pair of laterally-spaced upstanding conducting supports 56 (FIG. 4) and seats a plurality of fingers 57, which are engaged by the movable conducting bridging member 44in the closed-circuit position, as illustrated in FIGS. 2 and 4 of the drawings.

It will be noted that the auxiliary contact 21 has a flexible electrical connection 59 to the other terminal of the stationary accelerating coil 52, as shown more clearly in FIG. 5 of the drawings.

The opening operation of the circuit interrupter 1 will now be described. During the opening operation, the operating mechanism 33 is effective, either by manual initiation, or by the energization of a suitable trip relay responsive to fault current conditions, to effect rotation of the main operating crank-shaft 30 illustrated in FIG. 1 of the drawings. The rotation of the operating crank-shaft 30 effects downward motion of the two insulating operating links 28 to thereby cause initial downward opening movement of the operating member 25. This effects opening of the circuit at the auxiliary contacts 21, 22 and 35, 37, and subsequently, following the takeup of the lost-motion 46, carries the bridging clamping member 44 therewith together with the piston structure 9. The opening movement of the bridging member 44 breaks the contact engagement at the contact fingers 57 connected to the support casting 55 and causes the two accelerating coils 13 and 52 to be inserted into the series electrical circuit, as illustrated more clearly in the diagrammatic view of FIG. 7 of the drawings. The two coils 13 and 52 will attract each other and thereby cause accelerated motion of the piston member 9, which action is particularly desirable during heavy fault-current interruption, when there is considerable back-pressure exerted by the established arc 60 (FIG. 7).

From the foregoing, it will be apparent that during relatively low-current interruption, such as during the interruption of load currents, the operating mechanism 33 itself may be sufficient in power to effect fast-enough operation of the piston 9 within the operating cylinder 10 to cause the desired quantity of fluid 8 to flow through the orifice member 18 thereby to effect arc extinction. On the other hand, during heavy fault-current interruption, the back-pressure forces, which exist, are overcome in the instant invention by the augmenting action exerted by the attractive electromagnetic forces existing between the two accelerating coils 13, 52. Calculations show that with reasonable parameters, forces in excess of 10,000 lbs. are easily obtained under short-circuit conditions. However, this force is proportional to the square of the current, and the mechanism 33 must itself supply practically all the power for load-switching operation.

It will be obvious that once the arc 60 is interrupted, the electrical circuit passing through the coils 13, 52 is interrupted, and it is then comparatively easy for the operating mechanism 33 to carry the piston structure 9 and the movable contact structure 17 to the fully open-circuit position.

CLOSING OPERATION During the closing operation, when the device is applied on switching a high-voltage circuit, the arc will prestrike between contacts 6 and 7 before the device is completely closed. If a short circuit exists in the external circuit, and the short circuit current flows through coils 13 and 52, an attractive force will exist of such a magnitude that the closing operation cannot be completed. However, this is avoided in the following manner.

During a closing operation, the links 28 apply an upward force to the member 25 which takes up the lostmotion connection 46 closing contacts 21-22 and 3537 at once. It will be observed that the circuit is now L coil 52, contact 21, contact 22, member 25, contact 35, contact 37, member 44, rod 24, arcing contact 16, arc 60, contact 6 and L Coil 13 is not in the circuit and no attractive force exists between coils 13 and 52.

From the foregoing description of the operation of the circuit interrupter 1, it will be apparent that there is provided an improved fluid-blast type of circuit internlpter in which additional fluid-driving effort is attained by the insertion into series circuit of two accelerating coils 13, 52, one of which is a driving coil movable with the piston element 9 of the fluid-forcing means 26 of the interrupter 1. This additional force is dependent upon the current magnitude, so that during the interruption of heavy fault currents, an increased driving effort is obtained to cause additional fluid and pressure to be exerted upon the are 60 to effect its extinction.

Although there has been illustrated and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

I claim as my invention:

1. A fluid-blast circuit interrupter including a relatively stationary contact, means defining a relatively stationary operating cylinder having a reciprocally-movable piston movable therein, said piston carrying a movable contact which is cooperable with the relatively stationary contact to establish an arc, orifice means carried by the movable piston, the working opening motion of the piston within the operating cylinder forcing fluid under pressure through said orifice means and into engagement with the arc to effect its extinction, electromagnetic means for assisting in the driving motion of the piston including a movable accelerating coil carried by the movable piston and a stationary accelerating coil stationarily disposed adjacent the closed end of the operating cylinder, an electrical connection (20) electrically connecting said two accelerating coils together at all times, separable auxiliary transfer contact means disposed below the closed end of the operating cylinder and comprising first and second movable auxiliary transfer contact members (25, 44) having a lostmotion mechanical electrically insulated connection (46) with respect to each other, means electrically connecting the second movable auxiliary contact member (44) at all times with said movable contact carried by the piston, lineterminal means (55) disposed adjacent said closed end of the operating cylinder and making separable contact with the second movable auxiliary contact member (44), the second movable auxiliary contact member (44) insulatingly carrying a movable transfer contact (21), said lastmentioned movable transfer contact (21) having an electrical connection at all times to said first-mentioned electrical connection (20), said first movable auxiliary transfer contact member having a transfer contact (22) cooperable with said insulated movable transfer contact (21) and having a second transfer contact (35) cooperable in a separable manner from said second movable auxiliary transfer contact member (44), and operating means for initiating the opening and closing movements of the movable actuating member (25).

2. The combination of claim 1, wherein the electrical connection (20) comprises a piston rod extending through the closed end of the operating cylinder.

3. The combination of claim 1, wherein the stationary contact is tubular and cooperates with the movable orifice means so that fluid exhausts through the stationary tubular contact.

4. The combination of claim 1, wherein the first movable auxiliary transfer contact member (25) has trunnions at its opposite ends, and insulating operating links (28) are connected thereto to cause the actuation thereof.

5. The combination of claim 1, wherein the first movable auxiliary transfer contact member (25) is of channelshaped configuration and the second movable transfer member (44) is of generally elongated block form nesting within the channel-shaped member (25).

6. The combination of claim 3, wherein an arcing contact (16) projects within the tubular stationary contact (6) in the closed position.

7. The combination of claim 1, wherein the movable piston has two conducting piston rods (24), (40) electrically connecting the movable contact at all times with the second auxiliary transfer contact (44).

References Cited UNITED STATES PATENTS 2,503,243 4/ 1950 Cohen 335148 2,930,870 3/1960 Baer 335--186- X 2,933,575 4/ 1960 Baker.

3,238,340 3/1966 Lerch.

3,315,056 4/1967 Furakawa et al 33518 X FOREIGN PATENTS 1,142,201 1/ 1963 Germany. 1,206,056 12/ 1965 Germany.

514,359 1/1939 Great Britain. 1,190,079 4/ 1965 Germany. 1,206,056 12/1965 Germany.

ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERI-IYE, Assistant Examiner US. Cl. X.R. 

